Uses techniques developed here, for measuring 1) the electrical activity of intrinsic laryngeal muscles, 2) laryngeal airway resistance and 3) glottic aperture size in human subjects, to determine laryngeal function during respiration in wakefulness and sleep. Goal is to determine 1) the physiologic and pathophysiologic factors that control the respiratory-related activity of intrinsic laryngeal muscles, and 2) the net effect of changes in intrinsic laryngeal muscle activity on the respiratory function of the larynx.